Signaling system



March 31. 1925.

' 1,531,801 D. G. MCCAA 1 SIGNALING SYSTEM Filed May 2, 1922 4 Sheets-Sheet 1 g CS INVENTOR. H H SLAP-41 AMPLIFIER BY. a.

& Arrows March 31. 1925.- 1,5315801 D. G. M CAA.

SIGNALING SYSTEM Filed May 2', 1922 4 Sheets-sheaf 2 AMPLIFIER WJM BY Mmw 2 ATTORNEY.

March 31. 1925. I 1,531,801

D. G. M cAA SIGNALING SYSTEM I Filed law 2, 192? v 4 Sheets-Sheet 5 "Ii!" i IIIIPITHIIE 1 INVE TOR. v

A; 1 /0 1: W- v 1. M241,

$7 9. I ATTORNEYV I March 31. 1925. 1,531,801

D. G. .MCCAA SIGNALING :EYSTEM Filed May 2, 1922 4 Sheets-Sheet 4 41 ATTORNEY. I

Patented Mar. 31, 1925. I

UNITED STATES PATENT OFFICE.

DAVID e. MeCAA, or PALO A ro, CALIFORNIA.

SIGNALING SYSTEM.

' Application filed May 2, 1922. Serial No, 557,911.

Z all whom it may concern:

Be it known that I, DAVID G. MCCAA, a citizen of the United States, residing in Palo Alto, county of Santa Clara, State of California, have invented new and useful Improvements in Signaling Systems, of which the following is a specification.

My invention relates to signaling systems,

' and more particularly to such systems as radio and other systems in which it is de sirable to eliminate the efiects of static, strays, electrical atmospheric disturbances,

or in general, any disturbing electrical effects.

My invention residesin a method of and apparatus for eliminating disturbing effects of the character above referred to, including the effects due to or representing undesired signals. 1 1

In accordance with my invention, the sigrial-representing energy has or is caused to produce a substantially uniform or definite frequency, preferably an audio frequency, which causes or controls vibration, prefer ably at the same frequency, of a tangible or physical mass or structure, having suitable characteristics, which in turn directly, or. preferably indirectly through a second tan-' gible or physical mass or structure physically or mechanically coupled with the first men tioned mass or structure, generatesfor causes fluctuation of amplitude of a current which, preferably after amplification or other modification, operates .or controls a translating instrument for reproducing the signal, as in the form of sound or otherwise. 1

My invention resides in the method and apparatus hereinafter described and claimed. F or an understanding of my method, and

for an illustration of some of the various forms my apparatus may take, reference is to be had to the accompanying drawings,'in

section band device and the associated trical driver and generator.

Fig. 8 is an elevational view of a reed structure with associated diagrammatic representations of the electric'dri'ver' and generator. Fig. 9 is an elevational' view of a single elecsection band deviceorequivalent with diagrammatic representation ofthe electric driver and generator.

' Fig. 10 is a longitudinalisectional view,

partially in elevation, of air-coupled members with which are associated the electric driver and generator shown diagrammati Cally.

Referring to Fig. 1, A represents the an-' tenna orother absorption structure of a radio receiving station, or, in general, rep resents any conductor from 'whichthe signal-representing energy is received, as in a radio system, as aforesaid, or in a system employing a conductor or conductors be-' tween stations and traversed by current of suitable frequency, and more particularly,

a high frequency as in carrier wave s stems.

,F or brevity, and because of pre erence,

my invention will be described as utilized in connection with a radio receivingsystem in which the signals are transmitted by electro radiant energy of high frequency, and more particularly, hig frequency sustained or COIltlIlllOllS waves.

By wayof example, there may be connected between the antenna A and the earth or counter-capacity E -the"variable inductance L and the variable primary P of an oscillation transformer, L and P being shunted by the variable tuning condenser C. Coupled to the primary P is the secondary S shunted by the variable tuning condenserz C the difference of potential'at whose terminals is impressed, as through the condenser C shunted by a high resistance R, upon the grid 9 and cathode or filament f of a thermionic detector and amplifier V having'in addition'to the aforesaid grid and cathode theusual anode or plate a. The i filament f is maintained incandescent by current, whose magnitude is controlled by the variable resistance r, from the battery 6. The anode circuit has the battery or other suitable source of current B and the primary 7) of an audio frequency transformer whose secondary is 8. i

Related to the receiving apparatus as de scribed in any suitable manner is a source of high or radio frequency current D, which, in the example illustrated, is coupled to the grid circuit of the vacuum tube V by the transformer c. s v

As well understood in the radio art, if the signals in transmission are represented by undamped or sustained waves, or waves in trains with suitably small decrement, such received waves react with the current waves from the source D to produce beats whose frequency is the difference between the frequencies of the received energy and of the current from the source D. Generally, the beat frequency may be anything suitable or desirable, but in the example illustrated is of audio frequency,gas for example, of the order of 1000 per second. The result is that in. the secondary 8 there appears a current of audio or beat frequency, and thissecondary circuit is preferably-attuned to such audio or beat-frequency by means ofthe variable condenser G In the secondary circuit are connected the coils or winding d, d surrounding thesoft iron cores e, e disposed, respectively, upon the opposite poles of the permanently magnetized member -or permanent magnet it. Pivoted at z'is a soft iron armature jj supported by the upstanding members In, this structure being more clearly shown in Figs. 4 and 5, hereinafter referred to, A-

spring we of any suitable material, as phosphor bronze, engages with its upper end upon the upper side of the armature j and is secured or supported at its lowerend upon one; of the poles at of the cores 6. Carried by or supported on the armature 7' on its end opposite the spring mflis thevlight rod 0,

v i which is suitably attached to or merely pressed against the primary band F, which may be of steel or others'uitable metal, as bronze, brass, etc, or which may be of any suitable non-metallic material, as celluloid, fibre, wood, formica, and the like.

The band F may be-of any suitable cross section or shape, and may be in the form of a ribbon or-band, a wire or spring of circular or other cross section,-etc. Herein, however,

the term band is used, generically to cover all suitable forms, including the ribbon or true band form.

Suitably joined to the'b'and F orapreferably, as indicated, integral therewith or forming a continuation thereof, is the secondary band G, the bands F and G'being secured at one end atg and at the other end held in a clamp t having the threaded shank '14 on which isv threaded the thumb nut turning of which changesthe tension on the bands F, G to tune them or give them a desired or definite frequency or frequencies. The bands F, G are stretched over the upper ends of the blocks or members 41;, forming fulcra, frets, or the like determining the vibration lengths of the band sections Fand G.

at the same frequency or have the same natural period, and this is obtainable, when F and G are similar, in the sense of vibrating strings or bands, when the lengths of these sections between fulcra are equal. It will be understood, therefore, that preferably the member w engages the band mid-way between the terminal members w, w;

Associated with the band section G is a light rod 0 and an armature and magnet sys tem similar to that describedv in connection with' the band section F,

A second band structure comprising primary and secondary sections F and G may be employed in-ca'scade with the above described band structure comprising sections F and G. With the ban'dsections F 'and G are associated, respectively, magnet systems corresponding to those associated with the sections F aud t The coils d'of the magnet system associated with the band sectionG are connected in circuit with the coils (Z of tuning their circuit to the frequency of the band sections G and F and in particular to the frequency of the band section G. The coils d of the-magnet-system associated with the'band section G are connected in circuit with the primary w of an audio frequency transformer whose secondary is The circuit of the coils d and primary is attuned by the I condenser C to the frequency of the current in that circuit or the frequency of the band section G The transformer secondary q is connected, preferably through one or more thermionic or other amplifiers H, with the translating instrument T, which may be 'a telephone-receiver when'the signals are to be reproduced as sounds, or which may beany other suita'bleor convenient type of translating instrument or a relay controlling the signal translating instrument or other device of any's'uit'able character whatsover.

The operation is as follows The currentof audio frequency delivered by the secondary scauses the armature j of the-magnet system associated with the band section Fto vibrate at like frequency, thereby setting the bandsection F into vibration at the same frequency, the natural period of the band F preferably being equal to the natural period of the circuit of the secondary s. The band section F is a tangible or physical mass which: preferably has considerable mass or inertia so that it maynot be materially affected by or respond to a current ofirreghaving in general properties similar to those of the section F as to inertia, mass, and natural period. The band sections F and G are, in effect, mechanically coupled to each other, and this coupling, in a sense similar to coupling of electric circuits with each other, may be close or loose.

The mechanical coupling between the band sections F and G is the closer as the upper edge of the middle fulcrum w is the sharper or narrower as measured longitudinally of the band. When the upper edge of the fulcrum w is in effect a knife edge, the mechanical coupling between the sections F and G is close. A loose coupling between the sections may be effected by broadening or flattening the upper edge or end of the middle fulcrum w, as measured longitudinally of the band.

Furthermore, the flexibility of the band itself has an influence upon the closeness of coupling; for example, when the band is very flexible the coupling between the band sections will be loose, whereas when the band is relatively more rigid or stiff the coupling is the closer.

Loose coupling effects a higher degree of selectivity, as in the analogous case of loosely coupled electrical circuits. Loose coupling between the band sections F and G, and the other related band sections throughout this disclosure, may be obtained by employing a relatively flexible band and/or by making the upper edge of the fulcrum wflat or broad, at least as compared to a very sharp edge.

The coupling may be still further loosened, if suitable or desirable, by employing more than two band sections. Such an arrangement is indicated in Fig. 7, where between the band sections F and G there are three additional band sections, all preferably of the same natural period with F and G, the upper edges of the four intermediate fulcra w being, if suitable or desirable, suitably flattened or broadened.

The band section G, Fig. 1, driven by the band section F, drives and vibrates the armature 7' of the associated magnet system, of which the upstanding members is may be of magnetizable material, at a frequency corresponding with the frequency of vibration of the section G, thereby causing induction or generation in the windings d of a current whose frequency corresponds with the vibration frequency of the section G. This currentin turn traverses the windings (Z of the magnet system associated with the band section F of the second hand system, causing the armature j to vibrate at like frequency and drive and vibrate the band section F .at like frequency. The section G preferably loosely coupled to the section F is driven by F and in turn drives and vibrates the armature j of the system associated with section G at similar frequency, causing generation or induction in its windings d of current of like frequency, which traverses the primary m and induces in the secondary g a current of corresponding frequency which is them amplified, if

desired, and impressed upon the translating instrument T, which, if a telephone, will produce a sound or note corresponding with the frequency of the current delivered thereto by the secondary 3 which frequency corresponds with the frequency of the current, however produced as above described, in the secondary s or other equivalent or suitable receiving circuit.

By the method and apparatus described, undesired signals and the disturbing effects of static, strays, atmospherics or other natural electrical effects are selectively excluded. Static or other natural electrical disturbance occurs with irregularity or nonuniform frequency, and the response of the band structure is accordingly feeble, and tone selectivity and the anti-static property of the band system are both increased by increase in inertia of the primary band, as F.

While I have described the employment of two or more band systems in cascade, it will be understood thata single band system may be employed, though band systems in cascade effect ultimate higher selectivity. 7

It will further be understood that my invention is not limited to the employment of beats at the receiving station, but that any type of receiving apparatus may be employed which effects a current of definite or uniform frequency in the circuit of the coils (Z associated with the band section F. If the received energy'is that of continuous or sustained waves, it may be broken up into uniformly spaced groups, the dura tion of each group preferably being small or short compared with the duration of the shortest element of the telegraphic signal, as a dot. For example, by a so-called chopper or ticker the received sustained oscillations may be broken up into groups succeeding each other at the rate of 1000 per second, or at any other suitable rate.

The system is equally applicable to the case where the received sustained oscillations are modulated or varied in amplitude by a tone circuit or tone wheel. And the system is also utiliz'able in the case where at the transmitting station the sustained oscillations are caused to rise and fall in amplitude at a uniform or definite frequency, preferably audible frequency, by the effect of a tone circuit, tone wheel,

beat production or equivalent. The receiving apparatus is also utilizable in the case where the energy at the transmitting station is of constant amplitude, but in terrupted or broken up into wave groups at definite or uniform frequency. And in thecase of spark transmitters, my selective apparatus is utilizable in case the sparks succeed each other at definite or uniform frequency, to which frequency will then be attuned, as in the other cases, the audio frequency circuits and the band sections.

Therefore, in general, it will be understood that my invention is notlimited to any particular type of transmitting or receiving apparatus, Jut comprehends, generically, the production in the winding of a magnet system of a band, reed or equivalent device of a current, however caused or produced, of definite or uniform frequency to which the band, reed or equivalent is preferably at tuned.

Since each of the band systems or equivalent has considerable mass or inertia, once it is set into vitration by the associated magnet system or by a driver band section or equivalent, it will tend to continue in vibration for a considerable period, since its vibration decrement is relatively small, es-

Y pecially as compared with usual electrical circuits, owing to the tension, mass and stiffness or rigidity of the band. This property or characteristic of persistence of vibration on the part of the mechanical system causes reverberation, with resulting blurring or indistinctne'ss of the immediately succeeding signal elements. To prevent undesirable degree of reverberation or blurring, damping of the band or equivalent is resorted to.

In the system. described, this damping is effected electro-dynamically by tuning, as by condensers C C and C the circuits of the coils or windings d. lVith these circuits tuned to the frequency of the band sections with which they are associated, the kinetic energy of vibration of the band sections after cessation of the current or force which causes such vibration is consumed in generating or producing in the circuits currents of relatively high magnitude, due to the tuning or resonant effects, and the production or dissipation of such energy acts to dampen or quickly reduce the amplitude of the vibrations of the band sections.

This electro-dynamic damping is referred, and the tuning of the circuits as aforesaid,'in addition to effecting damping, serves also to cause the electric circuits to respond resonantly and cumulatively to the currents in them during the signal-producing timeor period.

While electro-dynamic damping or braking is preferred, it will be understood that any other suitable method or means for damping may be employed.

Referring to Figs. 4 and 5, there is asso' ciated with each or any band section, as 'F, the divic ed magnetic poles .2 and a of a magnet system comprising the core Z2 and yolres 0 the end of one of these yokes '0 terminating in the pole structure 2 consisting of two parts spaced from each other to permit passage of the aforesaid rod 0. The system is excited by the winding d traversed by uni-directional or direct current from any suitable source. The pole a is adjustable by the screw e toward and away from the band section F, so that the band shall be equally spaced between the upper and lower poles, whereby the band is normally not subjected to mechanical strain by either pole, since the fluxes act equally and oppositely upon the band, which by preference may be low re sistance magnetic material. After the band F has been set intovibration by a signalrepresenting current, and the band is vibratingdue to its persist/ency or inertia, the magnet system will act upon the band to dampen it, due to the magnetic fields established within the band and setting up therein eddy currents which effectively dampen its motion. This type of magnetic damping does not change the selectivity of the band. l i hen the band is under strain by flux of the damping magnet system a, 0. there exists a condition analogous to resistance damping in electrical circuits, and selectivity is reduced; but the poles 2 and a normally exert zero strain upon the band.

In Fig. 6 is shown a mechanical damping system in which a spring 7 bears upon the band through the pad of the felt or other suitable material. The pressure ortension exerted by the spring is adjustable by the screw M. I

A receiving system with which the band system is utilizable may be of the general type or character indicated in Fig. 2, where in there is employed a double audion or thermionic detector structure V whose grids g are simultaneously subjected to the same potential due to received energyl and the effects of static, atmospherics, etc., through the windings S S to which there is inductively coupled a primary P traversed by sustained radio frequency oscillations gene erated by the vacuum tube oscillator V The circuits of the anodes a, a of the thermionic structure V include audio frequency transformer primaries p and p inductively coupled to the secondary s, which latter and the associated band system, etc., correspond in structure and mode of operation in a general way with that describedin connection with F 1. So far as concerns detector action and the influence of received energy and static or atmospherics, their effect upon the secondary s is balanced out or substantially nil, whereas the beats, preferably of audio frequency, produced between the received signal energy and the oscillations produced by the oscillator V cumulatively affect the secondary s. It follows, therefore, that the effects of static, atmospherics, etc. are further eliminated before reaching the band system by rendering nil the effect of the detector action upon the secondary s, and reducing the effect of static and equivalent effects, from the fact that they do not from the sustained oscillations produced by the oscillator V produce regular or substantial beats, but, on the other hand, produce, if anything, a feeble effect upon the secondary s.

Accordingly, static and corresponding effects are materially reduced, and there exists then in the secondary s and the circuits as-,

sociated therewith current or audio fre quency corresponding with the frequency of the beats produced, and these are then caused to affect the band device F which in turn affects the band section G, which in turn affects the instrument T, the band system, as well as the above described static-reducing system, contributing to effective elimination of static and other irregular and undesired effects. A

The system in Fig. '3 is similar to that described in connection with Fig. 2, except, however, that the received energy reacts with that of the thermionic oscillator V to produce beats, preferably of inaudible frequency, by reaction with the received signal energy, and the static and other effects pro ducing imperfect and irregular beats therewith, with the result that in the secondary S there is reduced effect of static and the like, though the beats formed with the signal energy are uniform and pronounced.

These beat currents impress upon the grids g of a thermionic device V through the wind ings S and S similar potentials, with the result that the detector effect of these primary beats upon the secondary s is practically nil. The thermionic oscillator V produces sustained oscillations of a frequency which reactwith the primary beat frequency to produce secondary beats of preferably audio frequency, which, however, as in Fig. 2, cumulatively affect the secondary s, which latter is associated with windings d and a band system such as described in Figs. 1 and 2.

In Figs. 2 and 3 the primary P? is preferably rotatable or movablewith respect to the windings S S in order suitably to adjust the amplitude of the energy from the oscillator V to the amplitude of the signalrepresenting oscillations or currents in the windings S and S it being preferred, generally, that the amplitudes be approximately equal.

lVhile, as indicated in Figs. 1 and 2, it-is preferred that the vibrating mechanical member, as F, shall drive or set intovibration a second mechanical member, as G, it will be understood that the two armatures of the two systems involving the coils d,

that is, the primary or driver system and the secondary or generator system, may be asso-' ciated with one and the same vibrating member which, as indicated in Fig. 8, may be a reed, tuning fork or equivalent device R, attuned to the frequency of the current traversing the primary or driver coil system, which, in Fig. 8. is atv the left, while the generator or secondary electrical system is at the right.

Or, as indicated in Fig. 9, a single band F may co-act with the magnet systems of the primary or driver circuit and the secondary or generator circuit.

lVhen so using a single mechanical vibrating member, the armatures of the driver and secondary systems may be connected to the mechanical vibrating member, at the same point, as indicated in Fig. 8, or at different points, as indicated in Fig. 9.

In Fig. 10 the coupling between the magnet systems of the driver or primary circuit and the secondary or generator circuit is effected through an air column contained within the telescoping tube sections I, J closed, respectively, by the diaphragms K and L. These diaphragms may or may not be resonant or tuned to the frequency of the currents which they respectively respond to and generate. However, the air column is attuned to the driver or primary frequency.

In this arrangement the current of audio frequency in the driver or primary coils cl vibrates the diaphragm K at corresponding frequency, setting up in the tuned air column vibrations of the same frequency, which in turn vibrate the diaphragm L at similar frequency,'.with the result that there is generated in the secondary or generator circuit current of corresponding frequency. which may then be amplified and delivered to a translating device, as T, Fig. 1, or there may intervene a second air column system corresponding to the second hand system F G of Fig. 1.

The air column in Fig. 10 effects a substantially loose mechanical coupling between the driver: and secondary systems, and is also effective in reducing effects of currents of undesired frequencies or of irregularly 0r non-uniformly spaced currents, as those due to static. etc.

'VVhile in the foregoing description I have referred to the tuned mechanical elements, as

the'bands, reeds and air column, as having a period resonant with the driver or primary frequency, it shall be understood that these mechanical vibrating members may be dissonant'or out of tune with the current frequency. For example, in Figs. 1 and 2, the band sections F and F in Figs. 8 and 9 the reed R andband F, and in Fig. 10 the air column, may have a natural frequency different from that of the driver or primary current, whereby such current forces in the mechanically vibrating member vibrations at the primary or driver frequency, and the generator or secondary circuit in resonance with the driver or primary current is actuated or controlled by the dissonantmechanically vibrating member whose oscillations are forced. More particularly, as regards Figs. 1 and 2, the band section F may be dissonant to the frequency of the driver current from the secondary S, while the second band section G may be resonant to the frequency of the current supplied by the secondary S. And the same may be the relation between the bands F and G of Fig. 1. In other words, the driver sections may be dissonant to the currents actuating them while the secondary band sections G and G may be resonant to such current.

Or with a primary band section resonant to the driving frequency, the secondary section may be dissonant and the secondary electric circuit may be resonant to the primary frequency or resonant to the frequency of the secondary mechanical section.

While I have herein referred to the frequency of the driver or primary current and that of the band section or other mechanically vibrating element as equal, it Will be understood that the frequencies may be unequal in the sense that one may be any suitable multiple of the other. And this applies also to the secondary or driven mechanical elements, as G, G Fig. 1. Furthermore, the arrangement may be made such that the fre quency of the currents in the primary or driver and secondary or generator circuits are unequal, as by making one of them a multiple of the other.

It will further be understood that it is within the skill of the art to inter-pose be tween the secondary s or other source of driver or primary current and the magnet system which drives the mechanical vibrating member one or more stages of amplifiers similar to the arrangement of H, H in Figs. 1 and 2. And Where cascade arrangement of band or vibrating systems is em- .ployed, as in Fig. 1, one or more amplifiers may be introduced between the generator or secondary coils d, d of one band system and coils d, d of the driver or primary system of the second band system.

It will further be understood that my in vention is not limited to the dynamo-electric generation of-cu'rrent in the secondary or generator circuit, but comprehends also the production or generation of the current in the secondary system by any other method or means, as for example, by varying the resistance or impedance of a circuit including a source of energy, whereby there are fluctuations of amplitude of the currentequal to or corresponding with the frequency ofthe mechanically vibrating member.

For brevity in the appended claims, it shall be understood that reference to resonance or tuning of a mechanical system or ical system, and translating said secondary current.

2. The method of selectively receiving electrical signal energy, which consists in vibrating by a periodic signal-representing current a mechanical system resonant to the frequency of said current, generating by said mechanical system a secondary current of a frequency corresponding with the frequency of said vibrating system, and translating said secondary current.

3. The method of selectively receiving electrical signal energy, which consists in vibrating by a periodic signal-representing current a mechanical system resonant to the frequency of said current, generating by said vibratory system a secondary current of a frequency corresponding with the frequency of said periodic signal-representing current, and translating said secondary current.

4. The method of selectively receiving electrical signal energy, which consists in vibrating a mechanical system by a periodic signal-representing current, generating by said mechanical system a secondary current having a frequency corresponding with said periodic signal-representing current, reinforcing said secondary current by electrical resonance, and translating said reinforced secondary current.

5. The method of selectively receiving electrical signal energy, which consists in vibrating by a periodic signal-representing current a mechanical system having a natural period corresponding with the period of said signal-representing current, generating by said mechanical system a secondary current of a frequency corresponding with the frequency of said vibrating system, reinforcing said secondary current by electrical resonance, and translating said reinforced secondary current.

6. The method of selectively receiving electrical signal energy, which consists in vibrating by a periodic signal-representing current a mechanical system having a natural period corresponding with the period of said signal-representing current, generating by said mechanical system a current having a frequency corresponding with the frequency of said periodic signalrepresenting current, reinforcing said I secondary current by electrical resonance, and translating said reinforced secondary current.

7. The method of selectively receiving electrical signal energ Which consists in controlling vibration of a mechanical system by a periodic signal-repiesenting current, vibrating a' second mechanical system by said first mechanical system, generating by said second mechanical system a vibratory current, and translating said last named tem by a periodic signal-representing cur rent, vibrating a second mechanical system by said first mechanical system, at least one of said mechanical systems having a natural period corresponding with the period of said signal-representing current, generating by said second mechanical system a vibratory current, and translating said last named current.

10. The method of selectively receiving electrical signal energy, which consists in controlling vibration of a mechanical system by a periodic signal-representing current, vibrating a second mechanical system by said first mechanical system, said mechanical systems having equal natural periods of vibration, generating by said second mechanical system a vibratory current, and translat ing said last named current.

11. The method of selectively receiving electrical signal energy, which consists in controlling vibration of a mechanical system by a periodic signal-representing current, vibrating a second mechanical system by said first mechanical system, said mechanical systems having periods of vibration corresponding with the period of said signal-representing current, generating by said second mechanical system a vibratory current, and translating said last named current. q

12. The method of selectively receiving electrical signal energy, which consists in controlling vibration of a mechanical system by a periodic signal-representing current, vibrating a second -mecha-nical system by said first mechanical system, generating by said second mechanical system a vibratory current Whose frequency corresponds with the frequency of said signal-representing current, and translating said last named current. I r v i 13. The'method of selectively receiving electrical signal energy, which consists *in controlling vibration of a mechanical system by a periodicisignal representing current, vibrating a second mechanical system by said first mechanical system, generating by said second mechanical system a vibratory current whos'efrequency corresponds with the frequency of said first mechanical system, and translating said last named current. q I i 14:. The method of selectively receiving electrical signal energy, which consistsin controlling-vibration of a mechanical system by a periodic signal-representing current, mechanically vibrating a second mechanical system by said, first mechanical system, generating by said second mechanical system a vibratory current whose frequency corresponds with the frequency of said mechanical systems and said signalrepresenting current, and translating said last named current. a

15. The method of selectively receiving electrical signal energy, which consists in controlling vibration of a mechanical system by a periodic signal-representing current, mechanically vibrating a secondmechanical system by said first mechanical system, gen

crating bysaid second mechanical system a vibratory current, vibrating athird mechanical system by said vibratory current, producing by said third mechanical system a vibratory current, and translating said last named current.

16. The method of selectively receiving electrical signal energy, which consists in controlling vibration of a mechanical system by a periodic signal-representing current, mechanically vibrating a second mechanical system by said first mechanical system, controlling by said second mechanical system production of a vibratory current, vibrating a thirdmechanicalsystem by said vibratory current, mechanically vibrating a fourth mechanical system by said third mechanical system, producing a vibratory current by said fourth mechanical system, and translating said last named current.

17. Electrical signal receiving apparatus comprising a source ofperiodic signal-representing current, a vibrating member having a natural period corresponding with the period of said signal-representing current and vibrated thereby, means for generating a vibratory current by said member, and a signal-translating instrument controlled by said generated current. I

18. Electrical signal receiving apparatus comprising a source of periodic signal-representing current, a member vibrated by said current, a circuit, means for generating netic means,

in said circuit by said member a current having a frequency corresponding with the frequency of said signalrcpresenting current, means for rendering said circuit rcso nant to said frequency, and a signal-trans lating instrumentcontrolled bysaid circuit.

19. Electrical signal receiving apparatus comprising a circuit, means for causing in said circuit a periodic signalrepresenting current, a member vibrated under control of said current and having a natural period corresponding with the period of said signal-representing current, means for damping the vibrations of said member, a second circuit, means for producing in said second circuit a vibratory current under the control of said member, and'a signal-translating instrument controlled by said second circuit.

20. Electrical signal receiving apparatus comprising a circuit, means for causing in saidcircuit a periodic signal-representing current, a member vibrated under control of said current'and having a natural period corresponding with the period of said si-gmil-representing current, means {or damping the vibrations of said member comprising means for tuning said circuit to the period of said member, a second circuit, means for producing in said second circuit a vibratory current under the control of said member, and a signal-translating in.- strument controlled by said second circuit.

21. Electrical signal receiving apparatus comprising'a circuit, means for causing in said circuit a periodic signal-representing current, a vibrating member, electro-magnetic means controlled by the current in said circuit for actuating said member, means for damping said member comprising means for tuning the circuit of said electro-magmeans controlled by said vibratory member for producing a vibratory current, and means for translating said vibratory current.

22. Electrical signal receiving apparatus comprising a source of periodic signal-rep resenting current, vibratory members mechanically coupled to each other, means for vibrating one of said members under control of said signal-representing current, means for producing a vibratorycurrent under the control of another of said vibratory members, and means for translating said vibratory current. I

23. Electrical signal receiving apparatus comprising a source of periodic signal-representing current, vibratory members loose- 1y mechanically coupled to each other, means for vibrating one of said members under control of said signal-representing current, means for producing a vibratory current under the control of another of said vibratory members, and means for translating said vibratory current.

24. Electrical signal receiving apparatus comprising a source of periodic signal-representing current, vibratory members 1nechanically coupled to each other and at least one of them having a natural period corresponding With the period of said signal-representing current, means for vibrating one of said members under the control of said signal-representing current, means for producing a vibratory current under the control of another of said vibratory members, and means for translating said vibratory current.

25. Electrical signal receiving apparatus comprising a source of periodic signal-representing current, vibratory members loosely mechanically coupled to each other and at least one of them having a natural period corresponding with the period of said signal-representing current, means for vibrating one of said members under the control of said signal-representing current, means, for producing a vibratory current under the control oi another of said vibratory members, and means for translating said vibratory current.

26. Electrical signal receiving apparatus comprising a source of periodic signal-representing current, mechanically coupled vibratory members having natural periods corresponding With the period of said signal-representing current, means for vibrating one of said members under control of said signal-representing current, means for producing a vibratory current under the control of another of said vibratory mem bers, and means for translating said'vibratory current.

27. Electrical signal receiving apparatus comprising a source of periodic signal-representing current. coupled vibratory members means for vibrating one of said members under control of said signal-representing current, means for producing a vibratory current under control of another of said members, means for damping the vibrations of said other of said members, and means for translating said vibratory current.

28. Electrical signal receiving apparatus loo bers under control of said signal-represent- I ing current, means for producing a vibratory current under control of another of said members, means for damping the vi brations of said other'ot said members com prising means for rendering resonant the bers under control of said signal-representing current, a circuit, means for electrodynamically generating a current in said circuit by another of said vibratory members, and means for damping the vibrations of said other of said members comprising means for rendering said circuit resonant to a frequency corresponding with the natural frequency of said other of said members.

30. Electrical signal receiving apparatus comprising a circuit traversed by periodic signal-representing current, mechanically coupled vibratory members having a vibration frequency corresponding with the frequency of said signal-representing current, electro-magnetic means in said circuit for vibrating one of said members, means for tuning said circuit to the vibration frequency of one of said members, a second circuit, means for producing therein a periodic current of frequency corresponding with the vibration frequency of another of said members, means for tuning said second circuit to the vibration frequency of said other of said members, and a translating instrument controlled by said second circuit.

31. Electrical signal receiving apparatus comprising a source of periodic signal-representing current, a band vibrating in sections, means for vibrating one of said sections under control of said signal-representing current, means for producing a vibratory current under the control of another of said sections, and a translating instrument affect-- ed by said vibratory current.

32. Electrical signal receiving apparatus comprising a source of periodic signal-representing current, a band vibrating in sections loosely coupled to each other, means for vibrating one of said sections under control of said signal-representing current,

means for producing a vibratory current under the control of another of said sections,

and a translating instrument affected by said vibratory current.

33. Electrical signal receiving apparatus comprising a band vibrating in sections, a

circuit traversed by periodic signal-repre-' traversed by periodic signal-representing current, electro-niagnetic means in said circuit for vibrating one of said band sections, means for tuning said circuit to the frequency of said signal-representing current, i

a second circuit, means for producing therein a'vibratory current by another of said band sections, means for tuning said second circuit to the vibration frequency of the current produced therein, and a signal-transsecond circuit to the vibration frequency of the current produced therein, and a signaltranslating instrument controlled by said second circuit, said band sections having natural periods corresponding with theperiod of said signal-representing current.

36. Electrical signal receiving apparatus comprising a band vibrating in sections, a circuit traversed by periodic signal-representing current, electro-magnetic means in said circuit for vibrating one of said band sections, means for tuning said circuit to the frequency of said signal-representing current and the natural frequency of said one of said band sections, a second circuit, means for electro-dynamically generating therein a vibratory current by another of said band sections,*means for tuning said isecond circuit to the frequency of said other band section, and a translating device controlled by said second circuiti.

37. The combination with a source of periodic signal-representing current, of means producing a periodic current reacting with saidsignal-representing current to produce beats, mechanically coupled vibratory members, a circuit traversed by current of beat frequency for vibrating one of said members, means for producing a vibratory current under the control of another of said members, and a device for translating said vibratory current.

38. The combination with .a source of periodic signal-representing current, of a circuit, means for rendering substantially nil the direct eifect of saidv current upon said circuit, means producing a periodic current of different frequency reacting-withsaid signal-representing current to produce beats, means for affecting said circuit by said beats, a vibratory member vibrated under the control of said circu1t, vibratory rent,

til

dering said secondary beats etl'ective in said circuit, a vibratory member vibrated under the control of said circuit, means for :pro- 'ducing a vibratory current under the control of said vibratory member, and means for translating said vibratory current.

40. The combination with a source of periodic signal-representing current, of a resonant vibratory member vibrated by said current, signaL'translating means controlled by said vibratory member, and means for dainpin gzsaid member comprising means for ,clectro dynamica'lly generating thereby a damping current.

141, The combination with "a source of pa riod ic signal representing current, of a rescn'ant vibratory member vibrated by said current, signal-translating means controlled by said vibratory member, means for damping sa-i-d member comprising means for electro-dynamically generating thereby a damp ing current, and means for reinforcing said damping current by electrical resonance.

1-2. The combination with a source of poriodic signa l-representing current, oi a resonant vibratory member vibrated in accordance With said current, a circuit, and means for generating 1n 'SZUCl circuit by the vibrations of said member a damping our- 43. Tie'combinat-ion'with -a source of poriodic signal-representing current, of :a resonant vibratory member vibrated in accordance With said current, a circuit, means for -'gener-ating'in said circuit by-the vibrations of said member a damping current, and I means associated with said circuit for =reinforcing the damping current by electrical resonance.

44. The combination with a source of s igna l-representing current, of a resonantvibra'ti-ng member controlled thereby, a second resonant vibratory member coupled with and vibrated under the control or" said 'first nam'ed vibratory member, signal-translating means controlled by, said second vibratory member, and means for damping the Vibrations of said members upon cessation of "signal-representing current comprising meansfar generating there-by electrlcal damplng energy.

+15. The combination avi tl i a source of signarl-representing current, of a resonant vibrating member controlled thereby, :a second resonant Vibratory member coupled with and vibrated under the control of said first named vibratory member, signal-translating means controlled by said second vibratory member, means for damping the vibrations of said members upon cessation of signal-representing current comprising means for generating thereby electrical damping'energy, and means for re'inrorcing said dan'iping energy by electrical resonance.

4:6. Electrical signal-receiving apparatus con'iprisin-g :a source of periodic signal-representin current, mechanically coupled vi bratory members, means "for vibrating one of said members under control of said current, means controlled by another of said vibratory members for effecting period-i0 variations of current amplitude, and means for translating said last named current.

47. Electrical signal-receiving apparatus comprising a source of periodic signalrepresenting current, mechanically coupled resonant vibratory members, means for vibrating one of said members undercoi'itrol of said current, means for electro-dynamical-ly generating by another of said vibratory members a periodic current, and means for translating said last named current.

{58. Electrical signal-receiving apparatus comprising a circuit traversed by periodic signal-represent-ing current, an armature controlled by said circuit, a signal-translating circuit, a second armature associated with said second named circuit, and a resonant vibratory mechanical system con necting said armatures.

Electrical signal-receiving apparatus comprising a resonant vibratory mechanical system, means for vibrating said system under the control of signal-representing current, an armature mechanically connected to said system and vibrated thereby, and a signal-translating circuit in Which movement of said armature generates a periodic electro-motive-force.

50. Electrical signalreceiving apparatus comprising a resonant vibratory mech'anical system, means for vibrating said system under the control '01; signal-representing current, an armature mechanically connected to said system and vibrated thereby, a signaltra-nslating circuit in which movement of said armature generates a current, and electrical means for tuning said circuit to reinforce the current gcneratedtherein.

51. Electrical signal-receiving apparatus comprising a resonant vibratory mechanical system, an armature mechanically connected to said system for vibrating it, a circuit traversed :by periodic signalTrepr-esenting. current for vibratlng said armature, and

signal-translating means controlled by said vibratory system.

52. Electrical signal-receiving apparatus comprising a resonant vibratory mechanical system, an armature mechanically connected to said system for vibrating it, a circuit traversed by periodic signal-representing current for vibrating said armature, and signal-translating means controlled by said vibratory system, said armature when vibra-ted by said vibratory system upon cessa tion of signal current generating in said circuit a periodic damping current.

53. Electrical signal-receiving apparatuscomprisin a resonant vibratory mechanical system, an armature mechanically connected to said system for vlbrating 1t,'a circuit traversed by periodic signal-representing current for vibrating said armature, signaltranslating means controlled by said vibratory system, said armature When vibrated by said vibratory system upon cessation of signal current generating in said circuit a periodic damping current, and means for re inforcing said damping current by electrical resonance.

In testimony whereof I have hereunto affixed my signature this 26th day of April,

DAVID o, MCUAA. 

